CERES – The driver of a pickup truck ran a stop sign and plowed into a group of California junior high school students, killing one girl and injuring four others, police said as they interviewed witnesses Thursday to determine what caused the crash.

The driver, whom police identified as Larry Dale Duke of Ceres, struck the students as they walked to Mae Hensley Junior High around 9 a.m. Wednesday. The victims were all 13- and 14-year-old girls.

Witnesses told investigators that Duke ran a stop sign in his raised Chevrolet pickup and dragged one girl under the vehicle before stopping.

“He ran over one of them like a speed bump,” Nikalas Matthews, who saw the crash, told the Ceres Courier newspaper. “You could tell he wasn’t paying attention at all.”

Police said they’re also investigating witness reports that Duke, 45, was either on a cell phone or wearing earphones when he exited his truck. In California, the law prohibits drivers from using a handheld wireless telephone while driving. Drivers are also barred from wearing a headset or earplugs covering both ears.

Duke denied that he had been wearing earphones in an interview with KXTL-TV on Wednesday night. He said he didn’t know how the crash happened, but said he might have fallen asleep at the wheel.

“I’m so sorry this happened,” Duke told KXTL-TV. “I didn’t mean for it to happen.”

Ceres police spokesman Jose Berber said Thursday that Duke has not been arrested. Duke could not be reached for comment on Thursday.

Authorities have not released the name of the girl who died at the scene, but family and friends identified her as 13-year-old Danielle Tarancon-Leon.

The other victims’ injuries ranged from minor to serious, police said. Nancy Zavala, the victim who was transported to the U.C. Davis Medical Center in Sacramento by a Medi-flight helicopter, was listed in fair condition Thursday, according to hospital officials.

On Wednesday night, about 200 people gathered for a vigil at a nearby park for the victims. Family and friends are planning a mass for Tarancon-Leon on Friday.

“She was just a loving, spunky, fun, caring girl,” Danielle’s grandmother Trinidad Tarancon told the Modesto Bee. “It’s overwhelming to see the crowd of people here that cared about her and are showing their love for her.”